1. Field of the Invention
The present invention relates to robotic devices used in computer-assisted surgery. In particular, the invention relates to systems and methods for computer assisted laser-based instrument registration with a computed tomography (CT) and magnetic resonance (MR) imaging system.
2. Description of the Related Art
Minimally invasive and noninvasive procedures for surgery are gaining increased popularity mainly due to reduced trauma to patients and improved recovery time. One of the main problems encountered in minimally invasive procedures is, in contrast to open surgical procedures, a dramatic reduction in the surgeon's visual ability. Accordingly, radiological, ultrasonic, and magnetic resonance imaging techniques are employed to map anatomical geometry during intra-operative procedures.
Computed tomography (CT) guided percutaneous procedures are becoming increasingly popular in radiological interventions. CT guided interventions have been facilitated by the development of the CT fluoroscopy (CTF) imaging systems, which are a new generation of CT-scanners that allow for fluoro-imaging of a CT slice. Using the real-time cross-section image, the radiologist can manually orient and insert a procedure needle towards the target, provided that the skin entry point and the target are located in the current fluoro-slice. Even though the procedure is fast and precise in experienced hands, the major limitation of CTF is the relatively high radiation exposure to patient and physician. In order to make the real time adjustments in needle trajectory the physician's hand is often disposed in or near the scanning plane. Such hand exposure has been theoretically and empirically determined to be approximately 2 mGy per procedure [see, Nawfel R D, Judy P F, Silverman S G; Hooton S, Tuncali K, Adams D F: Patient and personnel exposure during at fluoroscopy-guided interventional procedures. Radiology (2000) 216:180-184]. If an annual dose limit of 500 mSv for the hands were presumed, a physician would be limited to performing only four CTF procedures per year.
A number of procedural techniques, shields, and passive needle holders have been proposed to reduce radiation exposure during such operations. Robotic systems have been investigated for eliminating radiation exposure and simultaneously increasing accuracy in radiological intervention.
One system using CT-fluoroscopy was reported by Loser and Navab, in Loser M H, Navab N: A new robotic system for visually controlled percutaneous interventions under CT fluoroscopy, MICCAI 1999, Lecture Notes in Computer Science, Springer-Verlag (2000) 1935:887-896. This system used a visual-servoing algorithm to orient the procedure needle based on fluoro-CT images. The approach demonstrated good targeting accuracy by using the procedure needle as a marker, without additional registration hardware. Even though the radiation exposure of the surgeon supervising the procedure from the control room is virtually zero, the patient is still being exposed to radiation during the robot's image-based servo orientation.
Susil et al. reported a registration method using a localization device (a modified Brown-Roberts-Wells frame) attached to the end-effector for the robot, which was further modified by Masamune. See Susil R C, Anderson J, Taylor R H: A Single Image Registration Method for CT Guided Interventions. MICCAI 1999, Lecture Notes in Computer Science, Springer-Verlag (1999) 1679:798-808; and Masamune K, Patriciu A, Stoianovici D, Susil R, Taylor R H, Fichtanger G, Kavoussi L R, Anderson J, Sakuma I, Dom T: Development-of CT-PAKY frame system—CT image guided Needle puncturing manipulator and a single slice registration for urological surgery, Proc. 8th annual meeting of JSCAS, Kyoto 1999:89-90. These methods present an advantage of providing the registration data from a single image slice. In addition the methods are not restricted to the use of CTF. However, the registration frame of these methods are cumbersome in the confined gantry space, and its initial positioning with respect to the CT active field imposed stringent constraints for interventional use.
Thus, there is a need for new and improved image based target guiding systems and methods that take advantage of commonly available imaging technology and solve problems with the prior art.